PRISM at Discovery Park

Abstract: In Micro Electro Mechanical System (MEMS) contacts, “stiction” or adhesion from capillary, van der Waals, electrostatic and chemical forces can all cause failure, limiting the device usage for contact relay miniaturization due the insufficient reliability. If the contact surfaces are also engaged in electrical current switching, e.g. RF MEMS switch, oscillations in the stress, temperature and electrostatic potential during a contact cycle result in the evolution of the topology, chemistry and physical properties of the two surfaces, degrading the characteristics of the junction with service. Various surface modification approaches, such as gold alloys and refractory coatings and self-assembled monolayers, have been unsuccessful in enabling the maintenance of these multifunctional (low adhesion, low resistivity) contacts. We explored metal nanoparticle liquids (NPLs) to provide reconfigurable and replenishable surface asperities that extend the durability by 10 to 100 times. These non-volatile NPLs are made of 5-20 nm Au and Pt nanoparticles with organic coronas consisting of surface tethered zero volatile ionic liquids. The nanoscopic size and corona fluidity are critical in providing sufficient electrical conductivity through nanoparticle jamming while maintaining a low contact adhesion by dynamically restoring a nanoscopic asperity texture via liquid surface migration. The alternative investigated approach had involved bioprocessed assembles of complex Au/Pd particles with attached peptide molecules, which showed a rival contact performance enhancement. Further tailoring of the electrical conductivity, thermal transport, and surface reconfigurability of the NPLs and versatility of the bi-metallic assemblies will provide options for a wide range of micro and macro electrical contacts, unlocking the bottleneck of MEMS switch reliability for high performance, broad band, long range telecommunication and phase array radar navigation capabilities.